Dna Base Composition of the Genus Hansenula

Abstract

The DNA base ratio (GC content) of 46 cultures of Hansenula and allied yeasts which represented 26 species or varieties was studied. The GC content of Hansenula DNA ranged from 28.5 to 46.3%. Intrageneric variation reached 15.6-17.8% in Hansenula sensu WICKERHAM, in Hansenula sensu LADDER and KREGER- VAN RIJ, in Hansenula emended by NoVAK and ZSOLT, and 11.0-12.7% in Hansenula group (genus) of TSUCHIYA et al. The frequency curve of the DNA base ratio demonstrated the presence of two large groups in the genus Hansenula. The first group had relatively high values of GC content with maximal frequency in a range of 40-42%. The second had relatively low values of GC content with the maximal frequency in a range of 32-34%. Species arranged in each line of the phylogenetic scheme of Hansenula proposed by WICKERHAM exhibited consistent DNA base ratios individually though exceptions were found, and so did the serological groups within Hansenula group (genus) of TSUCHIYA et al. A taxonomic and phylogenetic evaluation of DNA base ratio was discussed in relation to the delimitation of the genus Hansenula by several workers and the existence of several groups having similar DNA base ratio within the genus.In the previous paper (1), it was shown that the DNA base ratio (GC content) in ascosporogenous yeasts was relatively low, and that the range of distribution was not so large as that of asporogenous yeasts. However, intrageneric variations of the DNA base ratio of the ascosporogenous yeasts were rather large and the genera of this group of yeasts seemed not necessarily to consist of closely related species. This paper deals with the DNA base ratio of the genus Hansenula in relation to the taxonomic and phylogenetic schemes proposed by several workers.The genus Hansenula is considered to be a proper genus for studying the relationship among species because it is one of the most extensively studied genera of yeasts from the taxonomic and phylogenetic standpoints of view. MATERIALS AND METHODS Microorganisms.Forty-six cultures of Hansenula and allied yeasts which

Further Investigation on the Dna Base Composition of the Genus Hansenula

“…In phylogenetic line la, two new taxa, H. dimennae and H. saturnus var, subsu iciens, were added, and their GC contents were found to be similar to one another, being 42.0-44.1%. All the members of this line form Saturn-shaped ascospores, exhibit similar serological characteristics (10, 11), and are considered to make a natural taxonomic group as previously pointed out (1). Three species placed in line 1 b showed similar values of GC content (43.2-44.4%), though according to TSUCHIYA (11) and TSUCHIYA and IMAI (12), H. petersonii possessed an antigenic structure different from those of the other two species, C. utilis and H, jadinii.…”

“…DNA preparations from 46 cultures dealt with in a previous work (1) showed somewhat higher values of GC content (from 31.5 to 48.0%) than those (from 28.5 to 46.3%) previously reported, as listed in Table 2, by the use of the apparatus described by YAMADA and KOMAGATA (5). Seventeen cultures including new species described by WICKERHAM (6), which were newly investigated, showed GC values from 32.7 to 50.2% (Table 2 .…”

“…In additional to 46 cultures employed in a previous work (1), 17 cultures representing nine species and one variety were employed. Sources of these 17 cultures newly investigated are shown in Table 1.…”

“…In a previous paper (1 ), the present authors reported DNA base composition (GC content) of 46 strains of Hansenula and discussed the relation of this characteristic to taxonomy and phylogeny of this genus. Later, the values of GC contents previously reported (?)…”

DNA base composition of strains in the genera Rhodosporidium, Cystofilobasidium, and Rhodotorula determined by reversed-phase high-performance liquid chromatography.

“…Direct or indirect methods of determining guanine plus cytosine (G + C) content have been reported (1)(2)(3)(4)(5)(6)(7). Most investigators (8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)) use the thermal denaturation (Tm) method with the formula of MARMUR and DoTY (2) because the reproducibility of the Tm method, which was an indirect determination, was better than that of the direct method, e.g., UV absorption spectrum of the enzymatic hydrolyzate of DNA (5). But different research groups found different values of G + C content for essentially the same DNAs, e.g.…”